Prehistoric Humans Caused Climate Changes, Too?

It's almost quaint to think that our ancient ancestors, living some 10,000 years ago, may have altered the planet's climate, just like us. Though unlike today, a time when our thirst of fossil fuels is heating up the planet, a new study suggests that our distant relatives' hunger for mammoth meat could have played a hand in ancient climate change, long before the wheel was even invented.

Nice going, great-(x400)-grandpa.

According to a report from Science, it all stems back to the grazing habits of one of early man's favorite menu items, the wooly mammoth. The enormous herbivores were big eaters, grazing largely on small trees and grasses in northern regions of the globe, namely in what is now Siberia and Alaska. Their propensity to strip young trees of their leaves like modern-day elephants, however, may have helped dampen the growth of forests in this part of the world -- evidenced by a rapid increase in the number of trees which corresponds to a decline in mammoths.

While it would be impossible to say for certain that ancient humans were responsible for killing off the very last woolly mammoth, many researchers do believe over-hunting contributed to the animal's eventual extinction.

Once the number of tree-grazing mammoths dwindled enough, flora like the birch tree species 'Betula' flourished and spread unencumbered, transforming large regions of grassland into forests. Foliage in these new forests, in turn, was much darker than the grasses it overtook, meaning they absorbed and retained more heat. The trees, unchecked by the grazing mammoths, were also able to grow tall enough to not be covered completely by snow, allowing a gradual warming even in winter months.

Chris Doughty of the Carnegie Institution for Science, who worked on the study, figures that the disappearance of mammoths and the explosion of forests that followed 15 thousand years ago led to an average global warming of at least 0.1˚C -- and behind it, at least partially, was a small group of hungry humans.